Stable nitronyl nitroxide monoradical MATMP as novel monomer of reversible addition fragmentation chain transfer (RAFT) polymerization for ultrasensitive DNA detection

In this work, it came up a hydrophilic and stable nitronyl nitroxide monoradical 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl freeradical (MATMP) as new monomer of polymerization for DNA detection. The detection limit was over 1,000,000 times lower than 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives as electrochemical labels alone. Within this approach, a single biomolecule can be converted into the strong electrochemical signal, therefore lung cancer DNA can be detected at low concentration. For the first step, the HS-PNA probe was fixed on the surface of the Au electrode. After the target DNA was captured by complementary base pairing, 4-cyano-4-(phenylcarbonothioylthio) pentanoic acid (CPAD), chain transfer agent of RAFT polymerization, was bonded to target DNA as reaction via coordination bond of Zr4+. Electroactive polymers had grown by means of surface initiated thermally RAFT polymerization with MATMP as monomer. MATMP polymer significantly improves the electrochemical signal. This method can detect DNA from 0.01 fM to 10 pM, and detection limit is 1.51 aM. The sensitivity of this method is greater than that in most other reported signal amplification strategies of DNA biosensor, which indicates that it is appropriate for single nucleotide polymorphism analysis and will broaden prospects for biological molecules detection application.